March in Terrance B. Lettsome International Airport is the coldest month of the year. In March, the weather in Terrance B. Lettsome International Airport is typically warm. Average daily high temperature in March is about 26 degrees above zero. On average, Terrance B. Lettsome International Airport has 23 sunny, 6 partly cloudy, and 2 rainy days in March. The rains are usually light. March as well as January, February, and April is considered the most comfortable time to visit Terrance B. Lettsome International Airport.